tools/perf/bench/futex-lock-pi.c

   1 /*
   2  * Copyright (C) 2015 Davidlohr Bueso.
   3  */
   4
   5 /* For the CLR_() macros */
   6 #include <pthread.h>
   7
   8 #include <signal.h>
   9 #include "../util/stat.h"
  10 #include <subcmd/parse-options.h>
  11 #include <linux/compiler.h>
  12 #include <linux/kernel.h>
  13 #include <errno.h>
  14 #include "bench.h"
  15 #include "futex.h"
  16
  17 #include <err.h>
  18 #include <stdlib.h>
  19 #include <sys/time.h>
  20
  21 struct worker {
  22         int tid;
  23         u_int32_t *futex;
  24         pthread_t thread;
  25         unsigned long ops;
  26 };
  27
  28 static u_int32_t global_futex = 0;
  29 static struct worker *worker;
  30 static unsigned int nsecs = 10;
  31 static bool silent = false, multi = false;
  32 static bool done = false, fshared = false;
  33 static unsigned int ncpus, nthreads = 0;
  34 static int futex_flag = 0;
  35 struct timeval start, end, runtime;
  36 static pthread_mutex_t thread_lock;
  37 static unsigned int threads_starting;
  38 static struct stats throughput_stats;
  39 static pthread_cond_t thread_parent, thread_worker;
  40
  41 static const struct option options[] = {
  42         OPT_UINTEGER('t', "threads",  &nthreads, "Specify amount of threads"),
  43         OPT_UINTEGER('r', "runtime", &nsecs,     "Specify runtime (in seconds)"),
  44         OPT_BOOLEAN( 'M', "multi",   &multi,     "Use multiple futexes"),
  45         OPT_BOOLEAN( 's', "silent",  &silent,    "Silent mode: do not display data/details"),
  46         OPT_BOOLEAN( 'S', "shared",  &fshared,   "Use shared futexes instead of private ones"),
  47         OPT_END()
  48 };
  49
  50 static const char * const bench_futex_lock_pi_usage[] = {
  51         "perf bench futex lock-pi <options>",
  52         NULL
  53 };
  54
  55 static void print_summary(void)
  56 {
  57         unsigned long avg = avg_stats(&throughput_stats);
  58         double stddev = stddev_stats(&throughput_stats);
  59
  60         printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
  61                !silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg),
  62                (int) runtime.tv_sec);
  63 }
  64
  65 static void toggle_done(int sig __maybe_unused,
  66                         siginfo_t *info __maybe_unused,
  67                         void *uc __maybe_unused)
  68 {
  69         /* inform all threads that we're done for the day */
  70         done = true;
  71         gettimeofday(&end, NULL);
  72         timersub(&end, &start, &runtime);
  73 }
  74
  75 static void *workerfn(void *arg)
  76 {
  77         struct worker *w = (struct worker *) arg;
  78         unsigned long ops = w->ops;
  79
  80         pthread_mutex_lock(&thread_lock);
  81         threads_starting--;
  82         if (!threads_starting)
  83                 pthread_cond_signal(&thread_parent);
  84         pthread_cond_wait(&thread_worker, &thread_lock);
  85         pthread_mutex_unlock(&thread_lock);
  86
  87         do {
  88                 int ret;
  89         again:
  90                 ret = futex_lock_pi(w->futex, NULL, futex_flag);
  91
  92                 if (ret) { /* handle lock acquisition */
  93                         if (!silent)
  94                                 warn("thread %d: Could not lock pi-lock for %p (%d)",
  95                                      w->tid, w->futex, ret);
  96                         if (done)
  97                                 break;
  98
  99                         goto again;
 100                 }
 101
 102                 usleep(1);
 103                 ret = futex_unlock_pi(w->futex, futex_flag);
 104                 if (ret && !silent)
 105                         warn("thread %d: Could not unlock pi-lock for %p (%d)",
 106                              w->tid, w->futex, ret);
 107                 ops++; /* account for thread's share of work */
 108         }  while (!done);
 109
 110         w->ops = ops;
 111         return NULL;
 112 }
 113
 114 static void create_threads(struct worker *w, pthread_attr_t thread_attr)
 115 {
 116         cpu_set_t cpu;
 117         unsigned int i;
 118
 119         threads_starting = nthreads;
 120
 121         for (i = 0; i < nthreads; i++) {
 122                 worker[i].tid = i;
 123
 124                 if (multi) {
 125                         worker[i].futex = calloc(1, sizeof(u_int32_t));
 126                         if (!worker[i].futex)
 127                                 err(EXIT_FAILURE, "calloc");
 128                 } else
 129                         worker[i].futex = &global_futex;
 130
 131                 CPU_ZERO(&cpu);
 132                 CPU_SET(i % ncpus, &cpu);
 133
 134                 if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu))
 135                         err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
 136
 137                 if (pthread_create(&w[i].thread, &thread_attr, workerfn, &worker[i]))
 138                         err(EXIT_FAILURE, "pthread_create");
 139         }
 140 }
 141
 142 int bench_futex_lock_pi(int argc, const char **argv,
 143                         const char *prefix __maybe_unused)
 144 {
 145         int ret = 0;
 146         unsigned int i;
 147         struct sigaction act;
 148         pthread_attr_t thread_attr;
 149
 150         argc = parse_options(argc, argv, options, bench_futex_lock_pi_usage, 0);
 151         if (argc)
 152                 goto err;
 153
 154         ncpus = sysconf(_SC_NPROCESSORS_ONLN);
 155
 156         sigfillset(&act.sa_mask);
 157         act.sa_sigaction = toggle_done;
 158         sigaction(SIGINT, &act, NULL);
 159
 160         if (!nthreads)
 161                 nthreads = ncpus;
 162
 163         worker = calloc(nthreads, sizeof(*worker));
 164         if (!worker)
 165                 err(EXIT_FAILURE, "calloc");
 166
 167         if (!fshared)
 168                 futex_flag = FUTEX_PRIVATE_FLAG;
 169
 170         printf("Run summary [PID %d]: %d threads doing pi lock/unlock pairing for %d secs.\n\n",
 171                getpid(), nthreads, nsecs);
 172
 173         init_stats(&throughput_stats);
 174         pthread_mutex_init(&thread_lock, NULL);
 175         pthread_cond_init(&thread_parent, NULL);
 176         pthread_cond_init(&thread_worker, NULL);
 177
 178         threads_starting = nthreads;
 179         pthread_attr_init(&thread_attr);
 180         gettimeofday(&start, NULL);
 181
 182         create_threads(worker, thread_attr);
 183         pthread_attr_destroy(&thread_attr);
 184
 185         pthread_mutex_lock(&thread_lock);
 186         while (threads_starting)
 187                 pthread_cond_wait(&thread_parent, &thread_lock);
 188         pthread_cond_broadcast(&thread_worker);
 189         pthread_mutex_unlock(&thread_lock);
 190
 191         sleep(nsecs);
 192         toggle_done(0, NULL, NULL);
 193
 194         for (i = 0; i < nthreads; i++) {
 195                 ret = pthread_join(worker[i].thread, NULL);
 196                 if (ret)
 197                         err(EXIT_FAILURE, "pthread_join");
 198         }
 199
 200         /* cleanup & report results */
 201         pthread_cond_destroy(&thread_parent);
 202         pthread_cond_destroy(&thread_worker);
 203         pthread_mutex_destroy(&thread_lock);
 204
 205         for (i = 0; i < nthreads; i++) {
 206                 unsigned long t = worker[i].ops/runtime.tv_sec;
 207
 208                 update_stats(&throughput_stats, t);
 209                 if (!silent)
 210                         printf("[thread %3d] futex: %p [ %ld ops/sec ]\n",
 211                                worker[i].tid, worker[i].futex, t);
 212
 213                 if (multi)
 214                         free(worker[i].futex);
 215         }
 216
 217         print_summary();
 218
 219         free(worker);
 220         return ret;
 221 err:
 222         usage_with_options(bench_futex_lock_pi_usage, options);
 223         exit(EXIT_FAILURE);
 224 }